Convert AR-15 from 5.56 to 6.8mm SPC

BumbleBug · January 6, 2014, 11:24 AM

I've been doing some reading & I'm still a bit confused, so I'll just ask out right.

Just what is needed to convert an AR from 5.56 to 6.8mm? Just a new "Upper"? Are special magazines needed? Could just about any basic AR-15 lower be converted easily or are some brands more adaptable than others?

TIA

tahunua001 · January 6, 2014, 11:35 AM

upper, yes a new upper is required. you need the entire upper half including bolt carrier group.

magazines, no, you need special mags for the 6.8, standards wont work.

lowers. yes any in spec lower should work. it'll depend on who made yours. RRA lowers for example are generally built to tighter tolerances and don't like to mate to anything but an RRA upper although some people have been able t get such conversions to work. Areo/PSA, DPMS/Remington/Bushmaster, windham, DD, and most of the other reputable makers should all work just fine.

BumbleBug · January 6, 2014, 11:41 AM

The lower I'm considering is a PSA. I hear a lot about the "buffer"; does a new buffer spring come with a complete upper? Who makes the best mag's for this & what capacities are available?

Again TIA...

tahunua001 · January 6, 2014, 11:45 AM

the buffer and spring are generally considered part of the lower receiver group so I don't know for sure if it will be included or not. you can dump the weights from your standard buffer and fill it with lead shot to add a few OZ to it. a lot of times the spring is fine but it just needs a beefier buffer. I've done this with 7.62x39 conversions and it really helped out a lot.

dean1818 · January 6, 2014, 01:32 PM

You need a 6.8 Bolt, 6.8 Barrel, and 6.8 Mags

The current AR15 upper Reciever should be fine

The 6.8 is an great bullet. Puts the hurt on the Texas Piggies
(I bought the full upper)

I have the Bison Armory

I also use the standard AR15 buffer, which works well

January 6, 2014, 11:24 AM	#1
BumbleBug Senior Member Join Date: March 11, 2013 Location: Near Heart of Texas Posts: 870	Convert AR-15 from 5.56 to 6.8mm SPC I've been doing some reading & I'm still a bit confused, so I'll just ask out right. Just what is needed to convert an AR from 5.56 to 6.8mm? Just a new "Upper"? Are special magazines needed? Could just about any basic AR-15 lower be converted easily or are some brands more adaptable than others? TIA

January 6, 2014, 11:35 AM	#2
tahunua001 Senior Member Join Date: July 21, 2011 Location: Idaho Posts: 7,839	upper, yes a new upper is required. you need the entire upper half including bolt carrier group. magazines, no, you need special mags for the 6.8, standards wont work. lowers. yes any in spec lower should work. it'll depend on who made yours. RRA lowers for example are generally built to tighter tolerances and don't like to mate to anything but an RRA upper although some people have been able t get such conversions to work. Areo/PSA, DPMS/Remington/Bushmaster, windham, DD, and most of the other reputable makers should all work just fine. __________________ ignore my complete lack of capitalization. I still have no problem correcting your grammar. I never said half the stuff people said I did-Albert Einstein You can't believe everything you read on the internet-Benjamin Franklin

January 6, 2014, 11:41 AM	#3
BumbleBug Senior Member Join Date: March 11, 2013 Location: Near Heart of Texas Posts: 870	Thanks for the info... The lower I'm considering is a PSA. I hear a lot about the "buffer"; does a new buffer spring come with a complete upper? Who makes the best mag's for this & what capacities are available? Again TIA...

January 6, 2014, 11:45 AM	#4
tahunua001 Senior Member Join Date: July 21, 2011 Location: Idaho Posts: 7,839	the buffer and spring are generally considered part of the lower receiver group so I don't know for sure if it will be included or not. you can dump the weights from your standard buffer and fill it with lead shot to add a few OZ to it. a lot of times the spring is fine but it just needs a beefier buffer. I've done this with 7.62x39 conversions and it really helped out a lot. __________________ ignore my complete lack of capitalization. I still have no problem correcting your grammar. I never said half the stuff people said I did-Albert Einstein You can't believe everything you read on the internet-Benjamin Franklin

January 6, 2014, 01:32 PM	#5
dean1818 Senior Member Join Date: December 5, 2009 Location: Frisco Texas Posts: 844	You need a 6.8 Bolt, 6.8 Barrel, and 6.8 Mags The current AR15 upper Reciever should be fine The 6.8 is an great bullet. Puts the hurt on the Texas Piggies (I bought the full upper) I have the Bison Armory I also use the standard AR15 buffer, which works well __________________ An imperfect servant of my Lord and Saviour, Jesus Buying American made, wherever I still can